Process for refining sour hydrocarbon oil



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Patented Dec.,26, 1933 I 5:;

PROCESS REFINING soUR-nYDitooAm Lawrence M. Henderson, Narberth, 1a.,assignor I V to The Atlantic RefiningCompany, Philadclv phia, Pas acorporation of Pennsylvania No Drawing.

' Application humid 1931' I S erial:No.507,'l65 I v J I Claims' (o196'33) l".sou' r oil, that is, anoil which contains merca p' tans, withadoctor solutionwhich comprises an alkaline solution of leadoxlde orlitharge, where by lead mer'captides are formed by reaction of thedoctor solution withmercaptans contained in the (oil. Although leadmercaptides of low molece ular weight, for example, ethyl mercaptide;are

insoluble in oil and precipitate upon formation, the lead mercaptides ofhigher molecular weight are oil soluble and therefore remain in,solution .in the oil after the doctor solution is separated from theoil. For this reason, itis customary in the art to add elementary sulfurto the oil, thereby forming organic disulfides and insolublelead sulfideby reaction of the sulfur with the lead mercaptides. In practice theelementary sulfur is customarily added to the oil prior to orsimultaneously with the addition of the doctor solution, although it ispossible to withhold addition of the sulfur'until the spent doctorsolution has been separated. from the oil.

The addition of elementary sulfur to litharged oil-for the purposeof'breaking the oil, that is, for precipitating lead 5 hide isobjectionable in that an unavoidable excess of sulfur. is customarilyemployed. This excess sulfur remains in solution in the oil, therebyincreasing the total sulfur content thereof, and causing the oil toreact to the corrosion test.

A primary object of thepresent invention is to provide a process forbreaking so that the objections incident to breaking such an oil withelementary sulfur are avoided.

I have found that litharged oil may be broken, withthe consequentformation of an insoluble lead-containing precipitate, by treating thelitharged oil after separationof the doctorsolution therefrom with anaqueous solution of cupric chloride. L

In accordance with my invention a sour oil,

for instance, a sour gasolfne or lamp oil, is treated sodium plumbite ordoctor somanner. For example, be added to the oil and with a solution oflution in any well known the doctor solution may the mixture agitatedtoinsure proper contact. After proper reaction the mixture may besettled and the spent doctor solution which forms a lowlithargecl 1 oilswater erlayer may be separatedby draining. As cupric chloride'jis anacid salt it is preferred towash 7 the litharged oil withwatersubsequent tothe separation of the spent doctor solution.' Otherwisesmall amountsof cupricchloride will be lost .60

to the residual alkali of the lithargedjoil. The

water wash, however,' does not. remove from the oilthe leadmercaptides"which?were formed by "treatmentwith the doctor sol ion-.710' the l t a s d o l s h n'add anemia 5 solutionof cupric chloride,andthe resultant 'ture is thoroughly agitated to provide proper contactbetween the cup ric chloride and the lead mer:

.capltides'contained in the oil. There results the precipitatewhichisfoiind 7 0 to contain lead chloride. Upon completion of thereaction'the mixture is allowed to stand, with the formation of. atwo-layer system. The lower layer-of this system comprises thespentcupric I formation of a White chloride solution in admixture with theprecipitate of lead chloride, while the upper layerconsists of theoil'which is now sweet and free from lead and copper compounds. Theselayers may be separated, for example-by decanting the oil.

It is preferred that the-cupric chloride solution contain at least 10%cupric chloride at-the beginning of a run, and it is possible to employa saturated solution of cupric chloride to advantage. Ordinarily, acupric chloride solution of about 26% concentration is preferred.

The amount of cupric chloride solution necessary tocompletely break theoil and render it sweet will depend upon such factors as the amount oflead mercaptides present in the oil and the I concentration of thecupric chloride solution; Ito'o is to be pointed out that an advantageof myfprocess over the customary procedure of breaking litharged oilswith elementary sulfur is that the addition of an excess of my cupricchloride solu- 7 tion over the amount necessary to break the oil -95.isharmless, and in fact expedites' the reaction.

A further advantageof my process is that it may be carried outsemi-continuously or 'continuously, in a manner which one skilled in theart will immediately recognize.

erence to the following example of its operation.

A quantity of gasoline obtained by thermal decompositionof a gas oilfrom a West Texas crude oil was washed with a caustic solution to removehydrogen sulfide, and then treated with an aqueous solution of sodiumplumbite. After separa tion of the plumbite solution the gasoline waswashed. To 250 parts by volume of this gasoline was added25 parts byvolume of a 20% found to be sweet to the doctor test and free from leadcompounds. The same cupric chloride solution was used to break 10additional batches of the litharged oil, each batch comprising 250 partsby volume of oil. Thereafter the copper chloride solution failed tobreak further quantities of the litharged oil, indicating that thesolution was exhausted.

Whereas, the above description is specific to cupric chloride, othercupric compounds coming within the scope of my invention, namely othercupric halides or salt mixtures, such as a mixture of cupric sulfate andsodium chloride, which on being put into solutionionize to providecopper and. halide ions, are intended to be covered in the appendedclaims asequivalents, and the term cupric chloride as used in saidclaims is to be understood to include such equivalents.

. What I claim is:-

7 I. A processfor refining a sour hydrocarbon oil, which comprisestreating said oil with a solution of sodium plumbite, whereby oilsoluble lead compounds are formed separating the oil from said treatingsolution, treating the separated oil with an aqueous solution of cupricchloride, thereby to form lead compounds which are insoluble in oil, andseparating the oil from said aqueous solution and from insolublesubstances resulting from the treatment with said aqueous solution.

2. In the process of refining a sour hydrocarbon oil, which comprisestreating said oil with a solution of sodium plumbite, whereby oilsoluble lead compounds are formed, and separating said treating solutionfrom the oil, the step of precipitatinginsoluble compounds of lead fromsaid oil by treatment with an aqueous solution of cupric chloride.

3. A processfor refining a sour hydrocarbon oil, which comprisestreating said oil with a solution 7 of sodium plumbite, whereby oilsoluble lead compounds are formed separating the oil from said treatingsolution, treating the separated oil with an aqueous solution of copperchloride containing at least substantially 10% cupric chloride, therebytoiform lead compounds which are insoluble in cupric chloride, therebyto form lead compounds which are insoluble in oil, and separatingthe'oil 1()5 from said aqueous solution and from insoluble substancesresulting from the treatment withsaid aqueous solution. LAWRENCE M.HENDERSON.)

